Uncovering the structural, electronic and vibrational properties of atomically precise Pd_mCu_n clusters and their...

In this work, we address the structural stability, electronic properties and effect of metal-metal interaction on Raman spectra of icosahedral (Ih) Pd_mCu_n (m + n = 13) clusters using first principles calculations based on dispersion-corrected density functional theory (DFT-D2). Initially, we investigated the relative stability of Ih Pd_mCu_n clusters over monometallic Ih Pd₁₃ and Cu₁₃ clusters by calculating the average binding energy per atom, mixing energy, second order energy difference and average bond length. The Ih Pd₅Cu₈ is the most stable bimetallic cluster with the 2.88 eV, -0.218 eV and 0.678 eV average binding energy per atom, mixing energy and second order energy difference, respectively. The main goals of the present study are to figure out the chemical enhancement, modulation in electronic properties and Pd-Cu bond length in Ih Pd_mCu_n clusters after systematic doping of Cu-atom. Further, to examine the doping effect of Cu atom in Pd cluster, we have also analysed the Raman spectra of Ih Pd_mCu_n clusters. In case of Ih Cu₁₃ cluster, the contraction of Cu-Cu bond length as compared to its bulk form resulted in a significant blue-shift of characteristic Raman peak (212 cm^-1) of Ih Pd₁₃ cluster. Finally, the interaction mechanism of the CO₂ gas molecule over Pd-Cu alloy clusters have also been studied to understand the effect of composition on reactivity of CO₂ gas molecule.